1. Field of the Invention
The present invention relates generally to a method of making plywood from Arundo donax Ligneous (Arundo donax L.) or bamboo stalk that has been split longitudinally, divided into relatively even sections and then split into one or more layers of substantially equal thickness making for a more pliable material that can be woven into mats. Several of these mats are then layered and bonded to form plywood using an adhesive comprising resins and potash.
2. Description of the Related Art
Until now, Arundo donax or bamboo plywood has not been manufactured or marketed for structural material purposes due primarily to a lack of a cost-effective processing technique and the fact that, to a great extent, structural board and structural dimensional lumber are products that have been deemed incompatible with the cultures in localities where Arundo donax or bamboo growth is indigenous. Excluding North America, much of Europe and Japan, structural building materials have primarily been made from clay and cement block.
The use of Arundo donax or bamboo for production of board as a building construction material has yet to become popular in the United States for a host of reasons. Principally, with the large number of forests dotting the North American continent, the abundance of trees as a natural resource has supplied ample materials to feed the construction industry. Hence the technology for processing this raw material has greatly dominated the board industry for over 200 years and still prevails to this day.
The first and last American innovation of significance for bamboo board production was developed in the early 1970's. It was a method and machine for the making of bamboo veneer. Partially due to the relatively high cost of production (machine and equipment designs were in their infancy stage and resin choices were limited) along with the unavailability of base raw materials, this unique concept appeared impractical to the US market. Though Arundo donax and bamboo woods have rather significant inherent advantages over most other types of wood to the end user, including a much higher resistance to moisture, markets where the materials are indigenous have been far more receptive to value-added Arundo donax and bamboo products.
Over the last 12 to 15 years, different parts of Asia (namely Taiwan, Indonesia and Vietnam) have experimented with bamboo board production for non-structural applications.
One method involves splitting or quartering bamboo stalk in order to straighten the diameter curve of the linear stalk using heat and moisture. The stalks are then milled into uniform pieces and glued together by a mechanical press. This method produces an aesthetically attractive board product that is singled-layered and is commonly used for finished flooring.
More recently, in Asia, is the development of the technique of weaving bamboo stalks into mats. The mats are then layered and pressed into a board three mats or more thick (essentially producing a bamboo plywood) for the purposes of making strong yet light weight, stackable crates for the fishing industry. Recently in Vietnam, developers have been experimenting with layered bamboo mat board as a material for forming concrete.
Throughout the developing world, structural materials are usually made from cement/concrete, reinforced concrete or, for bigger- budget projects, steel. Value-added bamboo products are generally used for decorative purposes. However, many wood technologists recognize (even if only conceptually) that Arundo donax and most strains of bamboo, when processed into panels, yield a product of higher Internal Bond, Modulus of Rupture, and Modulus of Elasticity than the structural boards currently manufactured from soft woods in the United States today.
As the building construction industry in America continues to embrace panelization (prefabrication of wall systems in factory settings providing for greater on-site efficiencies), highly efficient materials such as Arundo donax and various strains of bamboo offer an attractive alternative to conventional wood from trees. Arundo donax and bamboo plants are classified as perennial grasses and therefore count as a renewable resource. Many areas in the southern U.S. are capable of large scale Arundo donax and bamboo production.
As global pressures continue to influence prices of structural board in the US, many developing countries are beginning to realize that they cannot solve twenty-first century housing shortages with eighteenth century (and older) technology: i.e., brick and mortar. Currently, wood composite board manufacturing plants are being set up in several Latin American countries including Mexico, Venezuela, and Brazil utilizing soft woods from forests, which are relatively scarce outside of North America, Russia, and northern China. Unlike in the Asian countries, little if any commercial development of Arundo donax or bamboo is being considered in Latin America and Africa, even though Arundo donax and bamboo are readily available.
Recent refinements in resins and techniques for plywood production in the US, improving cost efficiencies, are directly transferable to Arundo donax and bamboo layering. With the innovation of adding cost-efficient nanoscience technology and materials to substantially enhance fire retarding qualities, Arundo donax and various strains of bamboo suitable for plywood production are poised to have a significant impact as the next generation of structural building material for sustainable development.